Pulverized fuel burner



Sept. 20, 1932. YARROW 1,878,926

PULVERI ZED FUEL BURNER Filed June 15, 1929 Patented Sept. 2%, 1932"curiae sires HAROLD EDGAR YARROW, or GLASGOW, soo'rnnivn PULVERIZED FUELBURNER,"

Application filed June 13, 1929, Serial No. 370,5 69,and in GreatBritain August 24, 1998.

One object of the present invention is to obtain as short a flame aspossible consistent with eflicient combustion in a pulverized fuelburner, so that the size of the combus- 5 tion chamber can be keptwithin comparatively small limits. e

To ensure this result it is necessary to have a zone of high temperaturewhere the powdered fuel first enters the furnace, so that the ishydrocarbons in the fuel will be immediately set free and at the sametime the temperature of the residual particles of carbon will be raisedto such an extent that these particles will immediately combine with theoxygen supplied for their combustion.

According to the present invention this high temperature zone with itsconsequential advantages is obtained by so constructing the burner thatsome of the ignited fuel will '20 be drawn back towards and into theburner,

thereby heating one or more of the entering fuel mixture constitutentsby direct contact.

This is effected by introducing a Venturi constriction and nozzle in anannular passage through which one or more of the fuel mixtureconstituents pass to the combustion space, thereby reducing thepressurelocally and inducing a backward flow of ignited fuel towards and throughthe Venturi nozzle into the entering fuel constituent.

This and other features constituting the present invention are morespecifically described with reference to the accompanying drawing,wherein Fig. 1 is a central longi- 1 tudinal section of a burnerembodying the invention, and Fig. 2 is an end elevation thereof. 7

In the burner shown the pulverized fuel and primary air supply enter theouter tube H through the passage C, while the secondary air supply isderived from an air box or trunk 13 formed between the transverse,plates R. Air from the airbox or trunk B is supplied to the tube Hthrough a passage between vanes D mounted in said passage at an I ralityof nozzles, is preferably. directed someinclination to the radii of thetube H;(by which it is given a g'yratory motion) and thence to theannular inlet'S leading to the combustion chamber. r .7

The annular passage M between the outer tube H and the inner tube Eofthe burner is formed witha Venturi constriction at an'intermediatepoint, and at this point the inner burner tube E is'divided transverselyand has its'adj acent ends shaped to form an an-' nular constrictednozzle -N (or alternatively has nozzles formed in its wall) leading intothe Venturi constrictionin the'passage M. This annular nozzle-N, or anequivalent plu- '60 what towards the furnace end of the passage M. y I

The delivery or furnace end of the inner tube E is preferably fittedwith a sliding 8X:- tension piece Gr, which can be projected into thefurnace to a greater or less extent, as by means of a rod Q, which issuitably supported in the wall of the passage 0 and in the plate 0 whichcloses the outer end of the tubeE. This platemay be a fiat plate asshown in full lines in'Fig. 1-, or it may be of other suitable shape.

The reduction in pressure within the burner, due tothe'Venturiconstriction, in duces a backward liow'from the combustion space of hotgases which pass through the nozzle N and mingledirectly with the fuelconstituent or constituents whichenter the burner through .the passageC, so that the latterare heated to a comparatively high temperaturebefore their delivery to the furnace through the annular dischargeaperture S. The acent edges of the two parts of the tube Ejarepreferably made bulbous and shaped so as to form between them aconvergsing nozzle N, as stated abo'ye.

The result of his construction isthat'the fuel mixture constituent orconstituents I whichenterthrough the nozzle. C are delivcred to thecombustion space of .thefurnace at a high temperature and consequentlythere i i will be a zone of high temperature within the combustion ofthe fuel.

the'passage M. p g Having thus described the nature of the i form aconicalvortex of rapidly increasing area, with the result that there-isa reduction 4. A pulverized fuel burner according to claim 2, comprisingan air trunk surrounding the fuel conveying duct, passages leading fromsaid air trunk to the said duct near the discharge end thereof, andvanes in said passages inclined to the radii of said duct adaptedtoiimpart a whirling motion to the air passing therethrough. Intestimony whereof I have signed my name to this specification.

HAROLD'EDGAR YARROW.

of pressure at the edge T of "thes-leeve U which projects into thecombustion space and encircles the discharge end of the burnerflConsequently not only is the inner partpf the expanding Vortex ofburning fuel turned back 7 on itselfinto the mouthof. the tube G, butthe outer part of the expanding vortex is turned back on itself aroundthe rear edge of the sleeve Ufso that thefuelis exposed to directContact with the flame as it enters the furnace. Complete gasificationof the hydrocarbons is thereby obtained, and the carbon particles arealso raised to a temperature at which theyimmediately ignite, therebymaking the resulting flame short and intense;

g It may be desirable to give agyratory mo- 1 tion to the fuelconstituent or constituents which enter the burner through the inletpipe G prior to their discharge from the end of the passage M, and thismay be doneby a convenient arrangement of inclined or helical vanessituated at'or nearthe discharge end of i said invention and the bestmeans [know of carrying the same into practical effect, I claim 1. Apulverized fuel burner-comprising a duct to convey a fuel constituent toa furnace,

a second duct disposed within .the firstduct closed at one'end andleading at the. other end to the fun'a-ce, a Venturi constrictionformedby the inner and outersurfaces respectively of the first andsecond ducts, the second duct having in its wall an aperturesubstantially in the transverse planeof the I said Venturi constriction.

2. A'pulverlzed fuel burner comprising a duct to convey pulverized fujeland air to a furnace, a second duct situated within the firstduct andclosed at one end and leadingv at the other end into the furnace, aVenturi constrictionformed between the. inner and outer surfacesrespectively of the said first and second ducts, said second duct havingin its wall an aperture substantially in the trans-,

verse plane cfthesaid Venturi constrictiom 1 3, A pulverizedfuel burneraccording to claim 2, comprising an air trunk surroundincg the fuelconveying conduct and passages lea ing from said air trunk to the saidduct near the dlscharge end thereof; I

